How many years are you supposed to keep utility bill statements?

If you write off a portion (or all) the utility expenses for tax purposes (a dedicated home office, for example), keep the utility statements with your tax filing for seven years. Otherwise, you can hang on to them three months or so. Mark each for the date and method of payment. You have bank records as back-up.

Utility bills are not something you really even need to keep at all. However sometimes people do need them so if you choose to you can keep them. Keep them for a year and then toss them out if they were not needed during this time. Most of the time when they're needed they ask for your last one.